A US group argues printable weapons should be

New Scientist

Who would have thought it? Printing guns is
frowned upon. Even in the US.

Cody Wilson, a law student at the University of
Texas at Austin, found this out last week when Stratasys[1],
the company that made the uPrint SE 3D printer he was leasing, got
wind of his plans to design a 3D-printable[2]
handgun and took back their equipment.

"The company is less than thrilled with what
we're doing. They're trying to prevent me from breaking any laws
with their product," Wilson told New Scientist. With several
friends, he has founded a group called Defense
Distributed[3] to promote ideas about universal gun ownership.

If you build it&

In a letter to Wilson, lawyers for Stratasys
cited his lack of a
federal firearms manufacturer's licence[4] as their reason for the
repossession, adding that it does not knowingly allow its printers
to be used for illegal purposes. Wilson countered that his group's
aim is to disseminate a printable gun design online, not print guns
per se.

Stratasys wasn't buying that, and with good
reason: Defense Distributed's stated aims include the building of
two prototypes of differing complexity that can be printed on a
uPrint SE. If the guns work, the group will modify the designs for
use on entry-level 3D printers like RepRap[5], which
cost less than £1000.

So far, the plans are limited to computer-drawn
designs no physical prototype exists. But if Wilson and company
manage to build the first fully printable gun, they will risk more
than just running afoul of the law. Bullet propellants can
create temperatures of up to 1000 °C[6]. The powdered nylon
that entry-level 3D printers use for construction, called ABS,
cannot cope with that.

"The gunpowder explosion will probably be too
much for ABS and other plastics in low-end printers," says Stuart
Offer of 3D-printing firm 3T RPD[7] in Newbury, UK. In all
likelihood the gun would be destroyed, perhaps even blowing up in
the shooter's hands, after firing no more than a few rounds.

Fire when ready

3D printers exist that fuse metal powders using
laser or electron beams to produce sturdy, solid objects. But those
machines cost around £500,000, says Offer, who uses them to
make driver roll hoops for Formula 1 cars. And assembling a gun
isn't like snapping together Lego pieces each part must fit and
move precisely.

3D printers that fuse metal could make gun
components, but those parts would not make ready-to-fire guns, says
Dan Johns, an additive-manufacturing engineer based in Bristol, UK.
"The parts would need final, expert machining."

Still, as prices for more sophisticated printers
fall, printing functional weapons is likely to become an affordable
prospect. When that happens, governments will be faced with a
decision. Could they lean on internet service providers to seek out
and delete gun design files as they circulate online, as some ISPs
are now asked to police music and movie file-sharing?

That wouldn't work, says Wilson: "We know that
such efforts will be totally futile, with only random and
disproportionate enforcement."

Another possibility would be to more tightly
regulate ammunition,
as a few US states have done[8], so that shooters must get a
license before they can purchase bullets. But Wilson sees a way
around even this: print your own ammo. If the gun project has even
modest initial success, he says he expects to get working on this
too. "3D printable ammunition would be a joy to pursue."